Additive dispensing system and method

ABSTRACT

A liquid metering device that dispenses liquid into an adjacent reservoir at a precise ratio relative to the total volume of the adjacent reservoir as the reservoir is filled with liquid. The hydrostatic dispensing system includes an additive reservoir, a calibrated dispensing vessel, a hydrostatic pressure chamber, a pressure limiter, and a three-way valve that passively arms and dis-arms the system.

CROSS REFERENCE TO RELATED APPLICATION

This is a continuation-in-part of U.S. patent application Ser. No.12/573,751, entitled Additive dispensing system and method, filed Oct.5, 2008, now U.S. Pat. No. 8,267,108 and, as a continuation-in-partthereof, claims the benefit of provisional application 61/195,159 filedon Oct. 3, 2008, which is incorporated herein by reference and thepriority of which is claimed.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not applicable.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to an additive dispensing system which may beused for dispensing additive fluid into a storage tank while the storagetank is being filled with fluid. The invention finds application forfuel additive systems for fuel tanks of trucks and any equipment thathas a fuel tank to which mileage enhancing additives can be added. Theinvention also find application for adding corrosive additives such aschlorine to tanks so as to avoid corrosion to pumps, etc.

2. Background Art

Additive dispensing systems usually require external electrical powerfor various aspects of operation. The power is used to energize varioustypes of pumps, meters, level sensors and controls that cause the systemto add an additive to a tank in proportion to the fluid, e.g., fuel,being added to the reservoir tank.

FIG. 1 illustrates such a prior art system. Proportionality is achievedby metering both the fluid (10) being loaded into the reservoir (12) andthe fluid (20) being dispensed by an injector. Electronic signals fromboth meters (14, 24) are monitored and tabulated by a PLC (programmablelogic controller) (30) which, in conjunction with pre-programmedformulas, calculate pump performance requirements and send electricalpower to a variable speed pump (32) by means of a compound loopcontroller. The speed of the delivery pump (32) is determined by pulsesreceived from both additive and product meters (14, 24) which arecalculated and processed by the on-board PLC (30).

Such systems are very complex, are in most cases fragile, and aresubject to stray electrical interference typically found on highwaytrucks. In many cases, vehicle manufacturers will void their warrantiesif foreign equipment is installed that could pose a threat to theintegrity of the vehicle's on-board systems. Constant vibration,variable temperatures, harsh environments and inconsistent operatorinterfaces can make such systems undependable which significantlydiminishes fuel economy and performance of the vehicle.

Another example of prior art, is a system that measures fluid volumeeither by means of weight or some version of a level indicator (16) offluid (10) in the tank (12) to be additized. FIG. 2 illustrates such aprior art system. After the tank (12) is filled, and the volumemeasured, a calculated volume of additive (20) is then dispensed bymeans of a processor (30) and variable speed pump (32). Such systems aresubject to failure due to the delicate nature of tank level measuringdevices (16) when subjected to constant vibration found on variouscommercial vehicles. Like the meter paced system of FIG. 1, thesesystems are expensive and require interface with vehicle systems.

Fixed rate delivery systems such as described in FIG. 3, which may bepowered by air or electricity, depend on operator judgment in order toassure proper dosage when fuel is added to a fuel tank (12), since thesystems operate at a fixed delivery rate and must be activated manuallyby the operator fueling the vehicle. Since fueling rates of flow varysignificantly from station to station, it is impossible for this type ofsystem to meter the additive proportionately.

In general, previous and current devices available to the truckingindustry is often too expensive relative to the fuel savings realized byadditive injection and in addition, require high levels of maintenancewith unacceptable levels of dependability. All conventional additivesystems employ various pumps which in most cases depend on the integrityof valves, seals, diaphragms, piston seals and other dynamic seals forefficient operation requiring high levels of maintenance and incidenceof failure or out-of-specification performance.

3. Identification of Objects of the Invention

A primary object of the invention is to provide an additive dispensingsystem that eliminates the complexities and lack of dependability of theprior art systems described above.

Another object of the invention is to provide an additive dispensingsystem that provides precise ratio injection of an additive into a tankusing pressure forces available from the tank itself.

Another object of the invention is to provide an arrangement of valves,tubes, hydrostatic chamber and vertical column which dispenses liquidinto a larger volume reservoir.

Another object of the invention is to provide an arrangement forinjection of fluid into larger volume reservoirs without the use of anymoving parts, pumps or dynamic seals.

Another object of the invention is to provide an extremely simplearrangement which is capable of accurate, repeatable delivery ofadditive liquid into a larger volume of liquid.

Another object of the invention is to provide a system which dispensesfluids at a precise ratio into larger volume of liquid passively withoutthe need for an operator to “turn on” or “turn off” the system with theresult that the system provides an extremely dependable, consistentmethod for delivering a precise ratio for blending additive fluids intolarger volumes of fluids without depending on an operator interface.

Another object of the invention is to provide a simple method with whichto adjust the ratio of fluid being blended into a larger fluid volumewithout mechanical means.

Another object of the invention is to provide a low cost arrangement forprecise ratio dispensing of additive liquids into a larger volume ofliquid.

Another object of the invention is to provide a system to handlevolatile, dangerous additives that may be corrosive and aromatic wherethe system utilizes no dynamic seals or moving parts to dispense theadditive.

Another object of the invention is to provide an intrinsically safearrangement which precisely dispenses various fluids such as additivesinto larger volumes of liquids.

Another object of the invention is to provide a method for preciselydispensing various fluids such as additives.

Another object of the invention is to provide an additive arrangementwhereby an over-the-road truck driver may purchase fuel at various fuelsuppliers along the road and be assured that a desired additive isconsistently and accurately injected while the truck is being fueledwithout concern that he may add too much or too little to the fuel tankor that fuel may go untreated all together as a result of his error.

SUMMARY OF THE INVENTION

The objects identified above along with other features and advantagesare incorporated in an arrangement for dispensing additive fluid into afluid storage tank.

A dispensing vessel, preferably a vertical column, is provided having agross displacement reflecting a pre-determined ratio to the volume of afluid reservoir such as a fuel tank. The vessel or column has a verticalheight exactly the same as that of the adjacent fluid reservoir and ispositioned with the top and bottom of the vertical column beingprecisely aligned with the top and bottom of the adjacent reservoir. Thevertical column is filled with fluid that is to be added to the adjacentreservoir by means of an additive storage tank that is positioned sothat the bottom of the additive storage tank is at least as high as thetop of vertical column. The top of the vertical column is connected tothe bottom of the adjacent storage tank by means of a fluid line havingincluded therein a hydrostatic chamber, preferably having a diametergreater than the diameter of the vertical column. An additional liquidline selectively connects the bottom of the vertical column to theadditive storage tank or to an inlet fitting located at the top of theadjacent reservoir. A pressure limited is provided to limit the pressureat which fluid is supplied to the vertical column.

When fluid is added to the adjacent fuel reservoir, hydrostatic pressureis exerted at the bottom of the hydrostatic chamber equal to thepressure exerted in the tank by the liquid column height of the tank.Since the hydrostatic chamber is sealed and connected to the verticalcolumn which is full of fluid, the small amount of fluid present in thebottom of the hydrostatic chamber acts as a fluid piston, which, beingacted upon by the pressure exerted by the static head in the adjacentreservoir generates static pressure in the area above the fluid level inthe hydrostatic chamber and line that leads to the top of the verticalchamber. Since fluid is not compressible, as static head increases inthe reservoir, so does pressure within the chamber. The pressure exertedin the hydrostatic chamber forces the fluid in the vertical column downthrough the bottom port of the column, through the liquid line and up tothe top of the adjacent fuel storage tank where it is dispelled into theopen reservoir.

The rate of discharge of the vertical column into the adjacent tank isdirectly proportional to the static pressure exerted by the verticalcolumn height of the liquid in the adjacent reservoir.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is described in detail hereinafter on the basis of theembodiments represented in the accompanying figures, in which:

FIG. 1 illustrates a prior art system that measures both the fluid beingadded to the reservoir and the additive as it is being dispensed anduses an electronic controller to vary pump flow rate for proportioning;

FIG. 2 illustrates a prior art system that measures fluid level in thereservoir, and an on-board calculator determines the amount of additiverequired and instructs the electric powered pump to deliver thecalculated amount of additive required to proportionately treat thefluid in the reservoir;

FIG. 3 shows a typical prior art air powered injector that is notproportionate to flow, requiring an operator to stop and start thesystem as well as determine the total amount of additive required duringa specific fueling;

FIG. 4 is a system schematic according to one embodiment of theinvention showing major components of the system—a reservoir tank forcontaining the bulk fluid that is to receive measured amount ofadditive, a hydrostatic pressure chamber for creating a liquid pistonreflecting pressure created by column height of fluid in the reservoir,a calibrated vertical column for receiving and dispensing fluid additivein a measured quantity, an additive storage tank for storing the fluidadditive, and a three-way valve for selecting between dispensing andrecharge operation;

FIG. 5 is an enlarged side view of the calibrated vertical column ofFIG. 4 that stores additive equal to the maximum amount or ratio ofadditive that would be required by the system to be dispensed into thereservoir, showing a calibration rod used to displace volume in thecalibrated vertical column when a lesser dosage rate of additive isrequired;

FIG. 6A is a top view, partially cutaway, of the three-way activationvalve assembly of FIG. 4 mounted on the top of the receptacle adjacentto the fill opening according to a preferred embodiment of theinvention, showing three ports which direct the additive from theadditive tank to the calibrated vertical column while isolating thereservoir and conversely direct additive from the vertical column to thereservoir while isolating the additive tank;

FIG. 6B is a side view, partially cutaway of the three-way valveassembly of FIG. 6A;

FIG. 6C is a front view of the three-way valve assembly of FIG. 6A; and

FIG. 6D an isometric perspective view of the three-way activation valveof FIG. 6A, shown without the mounting apparatus.

FIG. 7 is a system schematic according to a preferred embodiment.

DESCRIPTION OF A PREFERRED EMBODIMENT OF THE INVENTION

An additive dispensing system 99 according to a preferred embodiment ofthe invention is illustrated in FIG. 4. A dispensing vessel 100,preferably a vertical column, is provided having a gross displacementreflecting a pre-determined ratio to the volume of a fluid reservoir 12,such as a fuel tank, and having a maximum column head when fully filledwith a selected additive. In other words, dispensing vessel 100 is sizedto produce the desired additive ratio for injection into reservoir 12.The dispensing vessel or column 100 has a vertical height h exactly thesame as that of the adjacent fluid reservoir 12 and is positioned withthe top level, also identified as the top surface, 102 and bottom level,also identified as the bottom surface, 101 of the vertical column 100being precisely aligned with the top level, also identified as thebottom surface 13 and bottom level, also identified as the bottomsurface, 11 of the adjacent reservoir 12. The vertical column 100 isfilled with fluid 20, a first fluid which may be an additive, that is tobe added to the adjacent reservoir 12 by means of an additive storagetank 22, which may be a container, that is positioned so that the bottomlevel 23 of the additive storage tank is at least as high as the toplevel 102 of vertical column 100 and which is associated with a pressurelimiter 700 to ensure additive 22 is supplied to vertical column 100 atpressure not exceeding the maximum column head. The top level 102 of thevertical column 100 is connected to the bottom level 11 of the adjacentstorage tank 12 by means of a fluid line 120, a first conduit, havingincluded therein a hydrostatic chamber 130, preferably having a diametergreater than the diameter of the vertical column 100. An additionalliquid line 124, a second conduit, selectively connects the bottom level101 of the vertical column 100 to the additive storage tank 12 or to aninlet fitting 15 located at the top level 13 of the adjacent reservoir12.

As the liquid (e.g., the fuel/additive mixture) level rises in reservoir12, a small quantity of its fluid contents 9 is introduced into thebottom of hydrostatic pressure chamber 130. Assuming in this operationcycle that calibrated vertical column 100 is completely full of additive20, a volume of air is now trapped in air line 132 (the portion of flowline 120, a first conduit, between hydrostatic chamber 130 and the toplevel 102 of vertical column 100). As the level of fluid 9 rises inreservoir 12 (such as by filling reservoir 12 with liquid 10, a firstliquid which may be a fuel, at opening 19, a fill opening), staticpressure is exerted on the volume of fluid 9 now trapped in the bottomof hydrostatic pressure chamber 130. Since fluid in the calibratedcolumn 100 and in the bottom of hydrostatic pressure chamber 130 is notcompressible, the air in air line 132 is compressed, and pressure isincreased in direct proportion to the column pressure exerted on thebottom of hydrostatic pressure chamber 130. The resulting pressureforces fluid 20 from calibrated vertical column 100 through liquid line124, a second conduit, through a three-way activation valve 150, andthrough injection line 15, all at a balanced rate relative to the liquidlevel fill rate in reservoir 12.

The diameter and vertical height of the hydrostatic pressure chamber 130has a direct relationship to the diameter of the calibrated verticalcolumn 100 used to measure additive 20. Since the liquid 9 in the bottomof the chamber 130 acts like a fluid piston, and the fluid pistoncompresses the air in the remaining portion of the chamber notcontaining liquid 9 and the air within the air pressure tube 132, it isadvantageous to minimize the volume of air in the chamber 130 byreducing the vertical height of the hydrostatic pressure chamber 130.The ratio of the area of a hydrostatic pressure chamber 130 to that ofthe calibrated vertical column 100 should be within a range of 10:1 to16:1, with the hydrostatic chamber 130 having the larger area.Therefore, if the diameter of the calibrated vertical chamber 100 is 1inch in diameter with an inside area of 0.785 square inches, thecorresponding hydrostatic pressure chamber should have a minimum insidearea of 7.85 square inches in order to displace the required additive ata proportionate rate.

As filling of reservoir 12 continues, the fluid 20 in calibrated column100 continues to be evacuated by the pressure in air line 132. Whenreservoir 12 is completely full, calibrated vertical column 100 isemptied, completing the dispensing of the precise ratio of additive 20into the reservoir 12. At any time throughout the reservoir fillingprocess, if filling were to stop, the additive 20 level in thecalibrated vertical column 100 will stop at the same proportional level.

As fluid 9 (e.g., fuel/additive mixture) is consumed from reservoir 12at any rate, the fluid column height in the reservoir 12 will bereduced, which correspondingly reduces the pressure exerted on the smallquantity of fluid 9 in the bottom of hydrostatic pressure chamber 130.Simultaneously, the compressed air present in the air line 132 andcalibrated vertical column 100 is reduced in direct proportion to thelevel in the reservoir 12, allowing fluid 20 from the additive tank 22to enter the calibrated vertical chamber 100 at the same rate (as afunction of fluid column height) as the fluid 9 exits reservoir 12.Regardless of the time duration of this reservoir emptying process, thecalibrated column 100 is refilled in preparation for the next dispensingcycle. With the level of fluid 9 in the reservoir 12 at any given level,the corresponding calibrated quantity of additive 20 is present in thecalibrated column 100.

In order for the dispensing system to function as described, it isnecessary for the bottom level 101 of dispensing vessel 100 to bealternately connected to the reservoir inlet fitting 15 or incommunication with the additive container or tank 22, as reservoir 12 isfilled and evacuated, respectively. This cyclical operation is effectedby three-way valve 150. Three-way activation valve 150 directs additivefrom calibrated vertical column 100 into the reservoir 12 in a first“dispensing” position while isolating the additive supply tank 22. In asecond “re-charge” position, three-way activation valve 150 directsadditive 20 originating from the additive tank 22 back to the calibratedvertical column 100 and isolates the reservoir 12. Three-way valve 150has a common port 152, a first port, that is connected to flow line 124,a second conduit, a first isolable port 151, a second port, connected toreservoir inlet 15, and a second isolable port 153, a third port, incommunication with additive container 22. In order to prevent theadditive 20 from freely draining from additive tank 22 into reservoir12, three-way valve 150 is arranged so that ports 151 and 153 are neverconnected to each other or to port 152 at the same time.

Referring to FIG. 5, if a different ratio of additive 20 should berequired relative to the capacity of reservoir 12, a calibration rod160, functioning as a displacement member, can be inserted into thecalibrated vertical column 100, which effectively reduces the capacityof the column 100 corresponding with the required volume of the newratio. A variety of displacement changes are available for the purposeof changing the desired ratio. When sizing the system initially, thecalibrated vertical column 100 must be sized to accommodate thenecessary volume of fluid for the maximum desired ratio of fluidrelative to the capacity of the reservoir. The size and volumedisplacement of the calibration rod can be adjusted to match a requiredratio. In addition to size and volume of the calibration rod, the shapeof the rod may also be adjusted, to reflect varying shaped fuel tanks,therefore making it possible to provide linear injection for acylindrical tank, for example.

Also, because additive 20 is dispensed as reservoir 12 is filled, andthis dispensed additive contributes to the fluid head, which in turncauses additional additive to be dispensed based on the combinedsolution, a slight non-linearity in dose rate is introduced. This erroris greater with greater dose rates and may be compensated for in thedesign of dispensing vessel 100 and/or displacement member orcalibration rod 160.

In a preferred embodiment, the calibrated vertical column 100 is thesame height as the corresponding height of the reservoir 12. The column100 is fixed to the installation either on the end of the reservoir 12or on a structure adjacent to the reservoir 12 so that the top level 102of the column 100 and the bottom level 101 of the column 100 correspondexactly to the top and bottom levels 13, 11 of the reservoir 12.

A portion 134 of the air pressure line 132 preferably extends beyond thetop level 102 of the calibrated vertical column 100 to a distance thatjust exceeds the top of the additive tank 22. This prevents additive 20from reaching the hydrostatic pressure chamber 130 during there-charging process.

The additive tank 22 is preferably located at a height sufficient toassure that the bottom of the tank 22 is no lower than approximately 1inch above the top level 102 of the calibrated vertical column 100 so asto provide sufficient head pressure to refill the calibrated column 100during the re-charging process.

Referring to FIG. 7, a pressure limiter 700 may also associated withadditive tank 22 to ensure the head pressure of the additive 20 suppliedvia flow line 124 does not exceed the maximum column head in calibratedvertical column 100. Pressure limiter 700 may be selected from any ofvarious devices known in the art. Pressure limiter 700 may beincorporated into additive tank 22 or may be a separate deviceintermediate the additive tank 22 and the three-way activation valve150. For example, where pressure limiter 700 is incorporated intoadditive tank 22, it may include a limiter 702 and a sealed additivetank 22, such that limiter 702 ensures that the additive tank 22 is notat atmospheric pressure. In another example, pressure limiter 700 may bean electrical, mechanical or electro-mechanical limiter 704 external ofthe additive tank 22, incorporated on the second path of flow line 124.Preferably, pressure limiter 700 comprises a pressure column 706,restricted to a maximum pressure column head of not more than themaximum column head, incorporated on the second path of flow line 124and which includes a level switch 708. Pressure column 706 is thus influid communication with the additive tank 22 and the dispensing vessel100. Level switch 708 may alternatively be removed if the communicationbetween the additive tank 22 and the pressure column 706 is accomplishedby a tube which permits the flow of additive 20 only so long as the headin pressure column 706 is less than maximum column head. Where levelswitch 708 is used, it is positioned in the pressure column 706 at aminimum fluid level in the pressure column 706 at the desired headpressure. When the level of additive 20 in pressure column 706 causesthe pressure column head to be below the maximum column head, levelswitch 708 activates a valve 710 intermediate the pressure column 706and the container 22 to permit the flow of additive 20 from the additivetank 22 to the pressure column 706. Level switch 708 terminates the flowof additive 20 from the additive tank 22 when the pressure column headequals the maximum column head. Where pressure column 706 is used, itfurther includes a vent 712, which vents to atmosphere at a height abovethe top of the maximum level of additive 20 in the additive tank 22.Vent 712 accomplishes multiple functions. By venting to atmosphere, vent710 permits the withdrawal of additive 20 from the pressure column 706to the column 100. Absent a vent 712, a vacuum could form in pressurecolumn 706, precluding operation. Further, vent 712 ensures that shouldlimit switch 708 and/or valve 710 fail in a manner which permitsadditive 20 to continue to flow into pressure column 706, having vent712 vent to atmosphere above the top of the maximum level of additive 20in the additive tank 22 ensures no additive 20 can exit the vent 712.

Referring to FIGS. 6A-6D, in embodiments used for trucks, for example,three-way valve 150 is preferably fastened to the reservoir 12 by meansof housing 157. Three-way valve 150 covers the tank fill cap 19 by meansof operator actuation arm 159, an operator. When arm 159 is rotated, itexposes the fill port 19 of the reservoir 12 and activates the system 99to direct fluid 20 from the calibrated vertical column 100 to thereservoir 12 while the reservoir is being filled with fluid 10.

Activation arm 159 is preferably spring loaded to cover lever fillopening 19 by default and must be rotated counter-clockwise to exposefill cap 19. Fill cap 19 is removed while holding operator 159 clear ofthe reservoir opening. With arm 159 rotated, three-way activation valve150 isolates the additive tank 22, and connects the bottom of column 100to the injection point 15. A fuel dispenser nozzle is inserted into thereservoir 12 through fill opening 19 with arm 159 allowed to returnagainst the fill nozzle. Fuel 10 is then delivered into reservoir 12.

When the fill nozzle is removed from the reservoir, and the tank lid isre-installed on the fill port 19, spring loaded arm 159 is allowed torotate back over the reservoir fill cap 19. Three-way activation valve150 thus shuts to the fluid path to injection point 15 andsimultaneously opens the fluid line in communication with the additivetank 22 and the bottom of the calibrated vertical column 100.

From the foregoing, it is evident that the additive dispensing systemaccording to the preferred embodiment of the invention does not utilizeconventional pumps or power of any kind other than static pressure foundwithin the components of the system during the process of filling andevacuating the reservoir. The system provides a precise, extremelydurable, inexpensive arrangement by which fluids such as additives(e.g., fuel efficiency additives) or disinfectants (e.g., chlorine) canbe added to reservoirs of fluid at precise ratios. The system providessmooth, pulse free, continuous, proportionate-to-flow blending of thedispensed fluid.

While some embodiments of the invention have been illustrated in detail,the invention is not limited to the embodiments shown; modifications andadaptations of the above embodiment may occur to those skilled in theart. Such modifications and adaptations are in the spirit and scope ofthe invention as set forth herein.

I claim:
 1. A system (99) for proportionally dispensing a liquidcomprising: a reservoir (12) for receiving a first liquid (10) intowhich a proportional dosage of a second liquid (20) is dispensed; saidreservoir (12) defining a bottom surface (11) and a top surface (13); acontainer (22) for storing said second liquid (20), said container (22)elevated above said top surface (13) of said reservoir (12); adispensing vessel (100) for transferring said second liquid (20) fromsaid container (22) into said reservoir (12), said dispensing vessel(100) defining a bottom surface (101) and a top surface (102), saiddispensing vessel (100) having a maximum dispensing vessel head whenfilled to said top surface (102) with said second liquid (20); a firstconduit (120) connecting the bottom surface (11) of said reservoir (12)to the top surface (102) of said dispensing vessel (100); a secondconduit (124) connecting the bottom surface (101) of said dispensingvessel (100) to said reservoir (12) and said container (22), said secondconduit (124) defining first and second mutually exclusive flow paths,said first flow path defined between the bottom surface (101) of saiddispensing vessel (100) and the top surface (13) of said reservoir (12)and said second flow path defined between said container (22) and thebottom surface (101) of said dispensing vessel (100); and a pressurelimiter (700), said pressure limiter (700) adapted to restrict thepressure of second liquid (20) in said second flow path to not in excessof said maximum dispensing vessel head; whereby an increased headresulting from an addition of said first liquid (10) to said reservoir(12) urges via said first conduit (120) a proportional volume of saidsecond liquid (20) to be dispensed from said dispensing vessel (100)into said reservoir (12) via said first flow path of said second conduit(124), and a decreased head resulting from an evacuation of saidreservoir (12) urges via said first conduit (120) said second liquid(20) to flow from said container (22) to said dispensing vessel (100)via said second flow path of said second conduit (124).
 2. The system(99) of claim 1 wherein: said reservoir (12) is characterized by across-sectional area that varies with height (h); and said dispensingvessel (100) has a vertical profile that varies with height (h) so thata fixed volume of said second liquid (20) per unit volume of said firstliquid (10) is dispensed into said reservoir (12) at all points betweenthe bottom surface (11) of the reservoir and the top surface (13) of thereservoir.
 3. The system (99) of claim 1 wherein: said bottom surface(101) of said dispensing vessel (100) is disposed at the same elevationas the bottom surface (11) of said reservoir (12); said top surface(102) of said dispensing vessel (100) is disposed at the same elevationas the top surface (13) of said reservoir (12); and a portion (134) ofsaid first conduit (120) is elevated above said container (22).
 4. Thesystem (99) of claim 1 further comprising: a hydrostatic chamber (130)disposed within said first conduit (120), said chamber (130) defining abottom surface that is connected to the bottom surface (11) of saidreservoir (12) and a top surface that is connected to the top surface(102) of said dispensing vessel (100).
 5. The system (99) of claim 4wherein: said hydrostatic chamber (130) is characterized by an averagehorizontal cross-sectional area that is greater than an averagehorizontal cross-sectional area of said dispensing vessel (100).
 6. Thesystem (99) of claim 5 wherein: a ratio of the average horizontalcross-sectional area of said hydrostatic chamber (130) to the averagehorizontal cross-sectional area of said dispensing vessel (100) rangesbetween 10:1 and 16:1.
 7. The system (99) of claim 1 further comprising:a displacement member (160) disposed in said dispensing vessel (100),whereby the presence of said displacement member (160) in saiddispensing vessel (100) lowers the dosage rate of said second liquid(20) per unit volume of said first liquid (10).
 8. The system (99) ofclaim 7 wherein: said reservoir (12) is characterized by across-sectional area that varies with height (h); and said displacementmember (160) has a vertical profile that varies with height (h) so thata fixed volume of said second liquid (20) per unit volume of said firstliquid (10) is dispensed from said dispensing vessel (100) containingsaid displacement member (160) at all points between the bottom surface(11) of the reservoir and the top surface (13) of the reservoir.
 9. Thesystem (99) of claim 1 further comprising: a three-way valve (150)disposed in said second conduit (124) so as to selectively enable saidfirst or second flow path.
 10. The system (99) of claim 9 wherein: saidthree-way valve (150) has a first port (152) connected to the bottomsurface (101) of said dispensing vessel (100), a second port (151)connected to said reservoir (12) and a third port (153) in communicationwith said container (22); said three-way valve (150) includes anoperator (159) to position said three-way valve (150) in a one of afirst flow path position, in which said first port (152) is in fluidcommunication with said second port (151) and said third port (153) isisolated, and a second flow path position, in which said second port(151) is isolated and said first port (152) is in fluid communicationwith said third port (153).
 11. The system (99) of claim 10 wherein:said reservoir (12) includes a fill opening (19) near said top surface(13) of said reservoir (12) for filling said reservoir (12) with saidfirst liquid (10); and said three-way valve (150) is coupled to saidreservoir (12) so that said operator (159) obstructs access to said fillopening (19) when said operator (159) is positioned in said second flowpath position and said operator (159) is clear of said fill opening (19)when said operator (159) is positioned in said first flow path position.12. The system (99) of claim 1 wherein: said dispensing vessel (100) isa calibrated vertical column.
 13. The system (99) of claim 12 whereinsaid pressure limiter (700) comprises: a pressure column (706), saidpressure column in fluid communication with said container (22) and saiddispensing vessel (100); a level switch (708) positioned in saidpressure column at a minimum fluid level in said pressure column; avalve (710) intermediate said pressure column (706) and said container(22) adapted to be activated by said level switch to permit flow of saidsecond fluid (20) to said pressure column (706); and a vent (712), saidvent (712) adapted to vent said pressure column (706) at atmosphericpressure at a height the maximum level of said second liquid (20) insaid container (22).
 14. A system (99) for dispensing a second liquid(20) proportionally into a first liquid (10), the system (99)comprising: a reservoir (12) defining a top surface (13) and a bottomsurface (11) and having an opening (19) at the top surface of saidreservoir (12) for receiving said first liquid (10); a container (22)for holding said second liquid (20), said container (22) defining a topand a bottom, the bottom of said container (22) elevated above the topsurface (13) of said reservoir (12); a dispensing vessel (100) defininga top surface (102) and a bottom surface (101), said dispensing vessel(100) equal to the height (h) of said reservoir (12) and disposedelevationally level therewith, said dispensing vessel (100) having amaximum dispensing vessel head when filled to said top surface (102)with said second liquid (20); a hydrostatic chamber (130) defining a topand a bottom, the bottom of said hydrostatic chamber (130) fluidlycoupled to the bottom surface (11) of said reservoir (12), the top ofsaid hydrostatic chamber (130) fluidly coupled to the top surface (102)of said dispensing vessel (100); a three-way valve (150) having first,second and third ports (152, 151, 153), said container (22) fluidlycoupled to said third port (153), said bottom surface (101) of saiddispensing vessel (100) fluidly coupled to said first port (152), andthe top surface (13) of said reservoir (12) fluidly coupled to saidsecond port (151), a first valve position connecting said first port(152) and said second port (151) while isolating said third port (153)and a second valve position connecting said first port (152) and saidthird port (153) while isolating said second port (151); and a pressurelimiter (700), said pressure limiter (700) adapted to restrict thepressure of second liquid (20) intermediate said container (22) and saidthird port (153) to not in excess of said maximum dispensing vesselhead.
 15. The system (99) of claim 14 wherein: said three-way valve(150) is mounted to said reservoir (12); and said three-way valve (150)includes an operator (159) that selectively covers a fill opening (19)of said reservoir (12).
 16. The system (99) of claim 14 wherein: saiddispensing vessel (100) is a calibrated vertical column.
 17. The system(99) of claim 14 further comprising: a calibrated displacement member(160) removably installed in said dispensing vessel (100).
 18. Thesystem (99) of claim 14 wherein said pressure limiter (700) comprises: apressure column (706), said pressure column in fluid communication withsaid container (22) and said dispensing vessel (100); a level switch(708) positioned in said pressure column at a minimum fluid level insaid pressure column; a valve (710) intermediate said pressure column(706) and said container (22) adapted to be activated by said levelswitch to permit flow of said second fluid (20) to said pressure column(706); and a vent (712), said vent (712) adapted to vent said pressurecolumn (706) at atmospheric pressure at a height the maximum level ofsaid second liquid (20) in said container (22).
 19. A method forproportionally dispensing a second liquid (20) into a first liquid (10)comprising the steps of: providing a reservoir (12) containing saidfirst liquid (10); providing a dispensing vessel (100) having a heightand elevation equal to that of said reservoir (12); coupling a top ofsaid dispensing vessel (100) to a bottom of said reservoir (12) so thatfluid head in said reservoir (12) pressurizes said dispensing vessel(100), said dispensing vessel (100) having a maximum dispensing vesselhead when filled to said top surface (102) with said second liquid (20);fluidly coupling a bottom (101) of said dispensing vessel (100) to apressure limiter (700), said pressure limiter (700) adapted to restrictthe pressure of said second liquid (20) intermediate a container (22)and a valve (150) in communication with said container (22) to not inexcess of said maximum dispensing vessel head; fluidly coupling thepressure limiter (700) to said container (22) having said second liquid(20) stored therein; filling said dispensing vessel (100) with saidsecond liquid (20) from said container (22) by lowering the pressure insaid dispensing vessel (100) by draining said reservoir (12); fluidlycoupling said bottom (101) of said dispensing vessel to the top (13) ofsaid reservoir (12); and dispensing said second liquid (20) from saiddispensing vessel (100) into said reservoir (12) by raising the pressurein said dispensing vessel (100) by filling said reservoir (12) with saidfirst liquid (10).
 20. The method of claim 19 further comprising thesteps of: installing a solid displacement member (160) into saiddispensing vessel (100) to reduce a dosage rate.
 21. The method of claim19 wherein said pressure limiter (700) comprises: a pressure column(706), said pressure column in fluid communication with said container(22) and said dispensing vessel (100); a level switch (708) positionedin said pressure column at a minimum fluid level in said pressurecolumn; a valve (710) intermediate said pressure column (706) and saidcontainer (22) adapted to be activated by said level switch to permitflow of said second fluid (20) to said pressure column (706); and a vent(712), said vent (712) adapted to vent said pressure column (706) atatmospheric pressure at a height the maximum level of said second liquid(20) in said container (22).
 22. The method of claim 19 furthercomprising the steps of: before filling said reservoir (12) with saidfirst liquid (10), fluidly coupling the bottom (101) of said dispensingvessel to the top (13) of said reservoir (12) by actuating an operator(159) of a three-way valve (150) to expose a fill opening (19) of saidreservoir (12).
 23. The method of claim 22 further comprising the stepof: after filling said reservoir (12) with said first liquid (10),fluidly coupling the bottom (101) of said dispensing vessel (100) tosaid container (22) by actuating said operator (159) of said three-wayvalve (150) to cover said fill opening (19) of said reservoir (12).